Treatment of ores containing coralt and nickel



May 7, 1946. c. F. ALLEN Erm. 2,399,845

TREATMENT OF ORES CONTAINING CBALT AND NICKEL Filed Feb. 6, 1945Dafa/'essen 2 F? Tail/'fly INVENTORS v CHHAM "5 F. 4 EN,

/V M. KIA/TPO,

ATTO R N EY Patented May 7,

NIKEL v charles F. Auen, Stamford, and Dan M. xenon,

Noroton, Conn., assignors to American Cyanamid-Company, New York, N. Y.,a corporation of Maine vApplication February 6, 1945, Serial No. 576,450

present invention and subjected to a selective 4 Claims.

The present invention relates to the beneficiavtion of cobalt-nickelores. More particularly, the

invention relates to an improved method of beneficlating cobalt andnickel sulilde ores by froth flotation using selective depressants forthe pyrlte and/or marcasite gangue which is frequently found in intimateassociation therewith.

Low-grade sulfide ores of cobalt and nickel,

particularly thse containing linnaeite and the complex cobalt-nickelsulilde, siegenite, are frequently found to contain other. sulildeminerals such as chalcopyrite and galena in a gangue of pyrite,marcasite, calcite and quartz. Commonly, the nickel-cobalt content ofthese ores is low, often being as little as 0.5 to 2% or less, of thevnickel and cobalt sulildes. To be commercially useful as a source of themetals, a concentrate containing at least 5% of cobalt in the combinedcobaltnickel product is desirable. The problem, therefore, involves twofactors, the removal of gangue and the reduction of the iron content.

Beneilciation by ordinary concentrating methods dependent upon surfaceconditions, such as froth flotation, is extremely 4diillcult. Not onlyis there an intimate association lof the minerals, but thecommonly-found pyrite and marcasite gangue, and the cobalt and nickelmineralsv are similarly affected by surface-conditioning reagents. Ingeneral, they exhibit similar reactions toward standard promoters,depressants, dispersants and the like. Consequently, an effectiveconcentration of the nickel andV cobalt minerals has been diilicult, ifnot impractical, to obtain. Nevertheless, because these ores represent aprincipal proportion of the available domestic source of both nickelandcobalt, the importance of a practicable method of concentrating thecobalt-nickel content is quite apparent.

It is, therefore, the principal object of the present invention todevelop a selective process of concentration by froth. notation wherebythe cobalt and nickel values may be effectively separated from thepyrite and marcasite gangue. It is also an object of this invention todevelop a vprocess which enables the production of a concentrate whichwhen sintered, will be sufficiently high in cobalt-nickel andsulcientlylow in iron to be commercially acceptable.

In general, the first step in accomplishing the principal objects of thepresent invention is to remove a copper-lead concentrate as thesemlnerals are present in appreciable amounts. The residue, oralternatively a bulk cobalt-nickel-iron concentrate obtained therefromby flotation, is conditioned with the novel depressants of the flotationof the cobalt-nickel sulides to produce a concentrate ,richer in cobaltand nickel, and

having the iron content minimized.

Surprisingly, it has been found that the alkali ferricy-anides and/orferrocyanides in combination witha suitable oxidizing agent act asselective depressants for pyrite and marcasite under operatingconditions. The selective action of this reagent combination is moststriking when it is considered that the principal gangue constituentsare iron sulfide minerals which ordinarily exhibit substantially thesame flotation characteristics as do the cobalt and nickel minerals, andthat the materials being used as depressants include alkali-ironcomplexes. Further, alkali cyanides which have been commonly used asreagents in lead-copper flotation do not produce any noticeablebeneiltwhen used in the cobalt-nickel concentration. I i

The practice of the present invention may be readily understood byreference to the accompanying drawing which diagrammatically illustratesthe steps in Aone preferred method of `carrying out the process. v

In general, the process of the present invention has the distinctadvantage of being easily carried out. namely the lead-copper float,several considerations have been found to be important in connectionwith the desired object of keeping the cobalt-nickel minerals out of thecopper-lead concentrate.. Preferably, the circuit should be alkaline.According to the present invention, a

PH of about 9 to 10 has been found'to be practically suitable, althoughthis may be varied have been found to be perfectly acceptable. Lime.being more economical and, when used in optimum amount, apparentlyhaving some specific enable. Otherwise, the lead-copper flotation is notparticularly unusual.

Excellent results have been obtained in this partici' the process usingas flotation reagents either the commercially available xanthate-typepromoters or those of the dithiopnosphate type such, for example, as the4ammonium salt of dcresyl dithiophosphoric acidand the sodium salt ofdi-sec. butyl dithiophosphoric acid in conjunction with a suitablealkali or alkaline-earth metal.

However, in the first stage of the process,

beneilcialeffect on the minerals, is perhaps prefl sired. They may beadded as required in ac- Commercial black calcium cyanide is quitosatisfactory so the more expensive alkali cyanides are not necessary.Also, the addition of a small amount of calcium sulte has also beenfound to be helpful as an aid to selectivity in some cases.

It has been found moet practical to add these reagents during thegrinding which is necessary to unlock the intimately associated varietyof minerals in the ore. If, however, it is so desired, the grinding canbe carried out and the reagents subsequently added 'in a separateconditioning step. Ii this is done, it is preferable that theconditioning be done at high solids but the operation may be carried outeither in the flotation machine or in a separate mixer. Preferably, apart oi' the promoter is added during, grinding and the remainderconditioned with the pulp after transfer to the flotation machine. Afrother is usually required during the lead-copper iiotation. Thecommercially available mixed cresylic acids frothers have been found towork well. Other types such as certain of the mixedl higher aliphaticalcohols, averaging about 7-8 carbon atoms, or pineoil may be used if sodecordance with standard practice.

The procedure up to this point may be considered more or less aspreparatory to the practice of the present invention which is found topotassium ferricyanide, sodium potassium ferricyanide and sodium orpotassium ierrocyanide. The ferrocyanides are usually cheaper and ifnecessary considerably more of them can be used without raising thetotal reagent cost. They are also usually much more readily available.Therei'ore. the ferrocyanides are perhaps preferable.

A number of oxidizing agents are available for the purpose. Of thosetried, the best results were obtained using alkali dichromates and/orpermanganates. Either may be used if so desired. The optimum results,however, are obtained using a mixture of dichromate and permanganatewith the ferroor fexricyanide. The eii'ectiveness of this depressantmixture is particularly surprising when it is considered that none ofthe materials when used individually produce concentrations of cobaltand nickel which are either as high in cobalt or nickel or as low iniron as can be obtained using the mixture. The invention will be morefully illustrated in commotion with the following example which is meantto be illustrative only and not by way of limitation. All parts are inpounds per ton of ore treated unless otherwise noted. In the followingexamples various reagents are represented by the following symbols:

A=Sodium, potassium ferricyanide B=Sodium ferrocyanide be highlycritical in many respects. The flota- C=Klcno7 tion is not particularlycritical as to the promoter D :mo l

used or as to the frother used. Commercial Example 1' xanthate promotersand higher aliphatic alcohol frothers were used in the development workA sample 0f 1W grade cobaltmkel Ore assay' ing about 0.6% Co and 0.8%Ni, was ground for but these may be replaced by equivalent reagents ofsimilar properties when so desired.

The critical procedure is in the use of the selective depressant mixturewhich enables the production of good cobalt-nickel concentrates whichare suiilciently low in iron to be commercially acceptable. As shown inthe drawing, the tailings from the copper-lead rougher flotation circuitare conditioned with the chosen cobaltnickel promoter and then subjectedto flotation flotation step in the notation cell for the production of abulk cobalt-nickel-iron sulfide concentrate. A gangue tailing isobtained which may be discarded. The bulk rougher concentrate, or acleaned concentrate if a cleaner stage is used, is then conditioned withthe depressants and subjected to a selective cobalt-nickel notationwhich yields the desired 4concentrate. Either the bulk rougher or the'selective cobalt-nickel flotation may be carried out in stages or insingle operations in accordance with standard practice.l

So far as the depressant mixture is concerned, it is found that twoconstituents are required, the rst .being a suitable alkali ferroorferricyanide and the second a suitable oxidizing 60 agent. A number ofavailable alkali ferroand in the presence of'a frother added during thefteen minutes at about solids with a mixture of 1.0 part lime, 0.5 partcalcium sulfite. 0.25 part commercial calcium cyanide and 0.04 part of apromoter comprising anammonia neutralized mixture of thiocarbanilid anddicresyli dithiophosphoric acid. After reduction to about 22% solids andconditioning for about one minute with 0.1 part of additional promoter,the pulp was floated for about four minutes to produce a vrougher Cu-Pbconcentrate. This concentrate was given a three minute float with 0.03part of an alcoholic type frother to produce thecleaner Cu-Pbconcentrate. I

' Example 2 A sample ot tailings produced according to Example 1 wasthen broken up into-a series of test samples which were successivelytreated to a two minute conditioning at ilotation density with 0.1 partof axanthate promoter and floated for iive minutes with 0.03 part of analcoholic frother. Thel resulting bulk concentrate from this treatment'was then conditioned for about flve minutes with the iron mineralsdepressant being tested and floated for about two minutes to produce thefinal Co-Ni-concentrate. Illustrative depressants used and theirmetallurgical results ferricyanides are lavailable such as sodium or areshown in the following table:

Iron deptslsnt Assays-concentrate Rm; Tw m Percent Percent Percent l A 0D l oo Ni Fo (72o lNi le v1.0 5.55 7.54 81.25 5&W, 59.@ 30.78

0.5 0.1 '5.1) 11.50 M ll '56.38 55.41 14.58

assaut We claim:

1. In concentrating suiiide minerals oi.' cobalt and nickel by i'rothflotation from an ore in which they are intimately associated with ironsulnde minerals, the improvement which comprises conditioning a pulpcontaining the cobaltfnickel sulides with a selective collector for thecobalt and nickel minerals and with a selective depressant mixture forthe iron sulfide minerals, said depressant mixture comprising at leastone compound selected from the group consisting of the alkaliterricyanides and the alkali ierrocyanides and at least one oxidizingagent selected from the group consisting of the alkali permanganates anddichromates, vsubjecting the conditioned pulp t0 forth notation andcollecting the resultant froth concentrate.

2. A process according to claim 1 in which the selective depressantmixture comprises at least one compound selected from the groupconsisting of the alkali feiricyanides and the alkali ferrocyanidestogether with an alkali permanganate.

3. A process according to claim 1 in which the selective depressantmixture comprises atleast one compound selected from the groupconsisting

